FIG. 12 is a cross section explaining a conventional dynamoelectric stator construction such as that described in Japanese Patent Laid-Open No. SHO 63-194543 (Gazette), for example, and FIGS. 13 to 17 are all diagrams explaining a method for manufacturing the conventional dynamoelectric stator.
This conventional dynamoelectric stator 1, as shown in FIG. 12, includes: a stator core 2; and a stator winding 4 installed in the stator core 2.
The stator core 2 is constructed by laminating a predetermined number of magnetic steel sheets punched into a predetermined shape, being constructed such that tooth portions 7 disposed so as to extend radially inward from an annular core back portion 6 are arranged at a predetermined pitch in a circumferential direction. Slots 3 are defined between adjacent tooth portions 7. Flange portions 5 are formed on tip portions of each of the tooth portions 7 so as to project circumferentially. These flange portions 5 serve a function of collecting magnetic flux, and also serve a function of preventing dislodgment of the stator winding 4 by closing approximately half a width of the openings of the slots 3.
The stator winding 4 is installed in the stator core 2 such that three-phase output can be obtained. In each of the slots 3, slot-housed portions 12a, described below, formed by pressing and deforming a portion of conductor wires 11 having a circular cross section into a rectangular cross section are housed so as to line up in single columns in a radial direction.
Furthermore, heat-tolerant insulators 8 are mounted into each of the slots 3, ensuring electrical insulation between the stator core 2 and the stator winding 4.
A method for forming the stator winding 4 will now be explained with reference to FIGS. 13 to 17.
First, as shown in FIG. 13, a first rectangular winding portion 12 is formed by winding a single conductor wire 11 having a circular cross section into a generally rectangular shape for six winds, and then winding the conductor wire 11 projecting from this rectangular winding portion 12 for six winds so as to form a second rectangular winding portion 12. A lap winding 10 having a plurality of rectangular winding portions 12 is prepared from the single conductor wire 11 by performing this operation repeatedly.
Next, each of the rectangular winding portions 12 of the lap winding 10 are mounted onto a press forming machine 13, as shown in FIG. 14. Here, six slot-housed portions 12a are stacked in single columns and inserted between a stopper 15 and slides 14 slidably supported by springs 16. Then, the slot-housed portions 12a are pressed in the direction of the arrow by a pusher 17. In this manner, as shown in FIG. 15, the slot-housed portions 12a of each of the rectangular winding portions 12 of the lap winding 10 are deformed into a rectangular cross section. Moreover, coil end portions 12b linking the slot-housed portions 12a have a circular cross section.
Then, the slot-housed portions 12a of the lap winding 10 are inserted from an inner circumferential side into each of the slots 3 mounted with the insulators 8 as shown in FIG. 16. Thereafter, tip surfaces of the tooth portions 7 are pressed by a roller, etc., in directions indicated by the arrows F in FIG. 17. In this manner, penetrating apertures 9 formed on the tip portions of the tooth portions 7 are crushed, and portions on first and second circumferential sides of the penetrating apertures 9 are pushed circumferentially outward to form the flange portions 5, obtaining the stator 1 shown in FIG. 12. In this stator 1, the slot-housed portions 12a having a rectangular cross section are housed in six layers in each of the slots 3 so as to line up in single columns in a radial direction with longitudinal axes of their rectangular cross sections aligned in a circumferential direction.
However, in the conventional method for manufacturing the stator 1, because six slot-housed portions 12a having a circular cross section are stacked in a single column and deformed by pressing them simultaneously with a pusher 17, the slot-housed portions 12a having a circular cross section are flattened while being in direct contact with each other, making it difficult to achieve a high degree of flatness on the long sides of each of the flattened slot-housed portions 12a. As a result, space factor when the slot-housed portions 12a are housed inside the slots 3 is reduced, giving rise to reductions in output. Furthermore, because first and second circumferential sides of the slot-housed portions 12a are restricted by the slides 14 and the stopper 15 when the slot-housed portions 12a are deformed by pressing, the flattened slot-housed portions 12a are deformed into a generally rectangular cross section with short sides also becoming flat surfaces. As a result, corner portions are formed on the short sides of the flattened slot-housed portions 12a, and when the slot-housed portions 12a are inserted into the slots 3, the corner portions of the slot-housed portions 12a rub against the inner circumferential side surfaces of the slots 3, damaging an electrically-insulating coating on the conductor wires 11, thereby making electrical insulation properties poor.